I have 24lb Accel injectors in a MAF TPI on a 350. My block is a GM Goodwrence 350 with Summit Iron Heads. 67cc Chanbers and 2.02 and 1.60 valves. My cam is a comp cams TPI cam with 260 duration and .444 lift. I have headers and a y with single 3" exhaust. I hope I'm pointing out enough mods to diagnose my problem. I bought all new gaskets, vacuum lines and sensors. I used a stock program AUJN with an injector constant of 22.2 and the BLMs are still near 140. I can't get this thing to richen up. Is there something I'm missing??

 

you may have to tweak the MAF tables abit for your part throttle considering you have a different set of heads and cam. My accels made my car run abit lean as well, i'm not sure if its the spray pattern or the 1.6 rockers i added that really leaned it out but it was abit lean. I never ran a injector constant below 24 tho

 

Shuanm

I would like to know what you end up doing to correct the condition you are experiencing. I have about the same set up as you and it seems I am having a similar experience.

I am just ordering the stuff needed to make an attempt at tuning. The only difference I can tell between our set ups is my chip is ABWN.

So if you wouldnt mind sharing your experience I would appreciate it.


thx
Jeff

 

I've replaced every part. I have a hi flo holley fuel pump rated to 120 PSI. I have 43 PSI at the rail at idle with vacuum and 49 without. I should be able to make it so rich it won't run supposedly. I have no cat as I don't have emissions here. My MAF is stock so I don't understand tweaking the tables. I'm pretty sure I'm not making 350hp.

 

its custom tuning via the prom and laptop. You open up the MAF tables 1-3 for part throttle and adjust the values up or down however you want to go. For rich add abit more to those numbers.

but it should run richer if the injector constant is set at 22 and at that fuel pressure you have going on.

is your o2 sensor new?

 

Make sure you changed both constants.
Single fire and Double fire. Just guessing here.

 

Now I'm back to what high blm's mean. I was under the impression that high blm's mean your engine is running lean, and your computer was compensating by adding more fuel. My oxygen sensor is a couple weeks old. The last one had the same results. I don't claim to know anything about tuning except that if you lower your injector constant you should be able to richen your mixture and get your blms down. Maybe I'm confused. It wouldn't be the first time.

 

Stock 350 chip, 24# svo, 50# fuel pressure,
cell 0 160
cell 1 150+
cell 2 128
cell 3 128
cell 5 128
cell 6 124
cell 7 128
cell 10 120
cell 14 124
cell 15 128

 

I wish my BLMs looked like that except for the 160s and 150s. Should I get bigger injectors? Maybe a different bin file to start with??

 

I have the bua $32 bin and have tried others $32 and $32b all the same. Is your fpr adjustable? If so try raising/lowering the fuel pressure to see if the blm's change.

A cold O2 will run lean, maybe try a heated 3 wire with the headers.

My stock vette exhaust (oem shorty header) will drop out the O2 at idle all the time. Volts go low first then just drop to zero, give some gas and back up it goes.

 

I had an AFPR from holley, but I never had anything stock to base it on so I went back to stock. If I raised the pressure way high, like 45 psi Idling with vacuum it would richen a bit, but when I stabbed on it the pressure went above 50psi so I turned it down where it would max at 49 and the BLMs went back up. I was told that 50psi was pushing it with stock rails and lines. Do the other 2 lines for the 3 wire sensor go to ground and 12v swiched?? I may give that a try.

 

A new coil fixed my problem. I also changed to aujm for my starting bin, but that isn't what made the change. The coil was the ticket.

 

yes use the fuel pump relay to power a second relay then let it run the O2.

Just wondering what your blm's are now, 1-15.

 

They went way down. Most were in the 112 to 115 range until I changed my injector constant back to 24. Now they are between 125 and 133. A little tweaking will get that right in shape I hope. Something was wrong with my accel coil. I've been using it for a year and it's been messed up the whole time. For some reason when I put the new coil in my ignition time was 12*, but it was set at 6* with the old coil. I'm not sure what it did, but I like it.

 

My cam has a 41 degree overlap. Did you have to adjust your idle 0-1 cells at all?